PROGNOSTIC DISCUSSION FOR LONG-LEAD OUTLOOKS CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EST THURSDAY FEBRUARY 14 2002 BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK . . . . . . . . THIS OUTLOOK REFLECTS THE EXPECTED U.S. CLIMATE ANOMALIES BASED ON THE LONG- TERM TREND AS ESTIMATED BY OCN - AND STATISTICALLY BASED RELATIONSHIPS BETWEEN RECENT OCEANIC AND ATMOSPHERIC CONDITIONS AND U.S. TEMPERATURE AND PRECIP- ITATION. DYNAMICAL FORECASTS FROM GENERAL CIRCULATION MODELS WERE ALSO USED FOR THE FIRST FOUR SEASONS. THE EXPECTED TRANSITION TO EL NINO CONDITIONS INFLUENCES THE OUTLOOK BEGINNING WITH THE JAS 2002 FORECAST. THE OUTLOOK FOR OND 2002 AND BEYOND ARE HEAVILY INFLUENCED BY THE ANTICIPATION OF AN EL NINO EVENT FOR NEXT WINTER. CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS PACIFIC SSTS ARE NOW ABOUT 1 DEG C ABOVE NORMAL ALONG THE EQUATOR FROM JUST WEST OF THE INTERNATIONAL DATE LINE TO ABOUT 150 W. TEMPERATURES NEAR THE SOUTH AMERICAN COAST ARE NEAR TO SLIGHTLY BELOW NORMAL. SUB-SURFACE PACIFIC OCEAN TEMPERATURES ALONG THE EQUATOR ARE SUBSTANTIALLY WARMER THAN NORMAL - AND THEIR EVOLUTION SUGGESTS THAT A WARM EVENT MAY BE UNDERWAY. THE DEPTH OF THE OCEANIC THERMOCLINE HAS INCREASED MARKEDLY IN THE EAST-CENTRAL PACIFIC IN RECENT WEEKS. ATMOSPHERIC INDICIES - HOWEVER - CONTINUE TO REFLECT NEUTRAL ENSO CONDITIONS AND ARE DOMINATED BY MJO ACTIVITIY WHICH HAS BEEN VIGOROUS IN THE LAST FEW MONTHS. THE EXTRATROPICAL NORTH PACIFIC SSTS CONTINUE TO BE BELOW NORMAL OVER A LARGE AREA EXTENDING FROM THE MID-PACIFIC EASTWARD TO THE NORTH AMERICAN COAST. . . . . . . . . PROGNOSTIC DISCUSSION OF SST FORECASTS MOST STATISTICAL AND DYNAMICAL PREDICTIONS OF NINO 3.4 SSTS INDICATE A GRADUAL WARMING FOR THE NEXT SEVERAL MONTHS. TWO OF THE THREE MAIN TOOLS RUN AT NCEP FORECAST WEAK TO MODERATE WARM EPISODE (EL NINO) CONDITIONS TO DEVELOP BY SUMMER (CCA AND THE NCEP NUMERICAL MODEL) - WHILE THE CONSTRUCTED ANALOG (CA) METHOD KEEPS TEMPERATURES NEAR NORMAL THROUGH THE REMAINDER OF 2002. THE CA PREDICTION DOES NOT ACCOUNT FOR THE SUB-SURFACE OBSERVATIONS WHICH HAVE CHANGED DRAMATICALLY IN THE LAST FEW MONTH - WHICH MAY EXPLAIN ITS LACK OF RESPONSE TO RECENT CHANGES. THE MOST RECENT OBSERVATIONS OF SSTS IN THE CENTRAL PACIFIC - ALONG WITH THE SUB SURFACE STRUCTURE SUPPORTS THE ENSO PREDICTION TOOLS THAT FAVOR WARMER SSTS - HENCE THE OFFICIAL FORECAST IS FOR A WARM ENSO EVENT TO DEVELOP WITHIN THE NEXT FEW MONTHS. THUS THIS MONTH OUTLOOK WILL FOLLOW THE FORECAST FROM THE NCEP MODEL AND CCA AND NOT THE CA OR THE REGRESSION CONSOLIDATION FORECAST. ABOVE NORMAL CENTRAL EQUATORIAL PACIFIC SSTS ARE ALSO SUPPORTED BY MANY MODELS RUN AT OTHER CLIMATE CENTERS AS WELL AS THE CPC MARKOV STATISTICAL MODEL. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK THE STATISTICAL TOOLS ... CCA - OCN - SMLR ... WERE CONSULTED AT ALL LEAD TIMES. DYNAMICAL MODEL FORECASTS FROM NCEP AND OTHER FORECAST CENTERS WERE CONSULTED FOR THE PERIOD MAM - JJA 2002. THE LARGE SCALE CIRCULATION PATTERNS ARE ANTICIPATED TO REFLECT WARM ENSO CONDITIONS BY LATE SUMMER AND INTO THE NEXT COOL SEASON - SO WARM EVENT COMPOSITES WERE CONSULTED FOR SEASONS PAST JAS 2002. . . . . . . . . PROGNOSTIC DISCUSSION OF OUTLOOKS - MAM 2002 TO FMA 2003 TEMPERATURE: THERE IS A GENERAL CONSENSUS FOR ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE WESTERN U.S. AMONG THE DYNAMICAL MODELS AND THE STATISTICAL TOOLS DURING MAM AND AMJ 2002. THE NCEP MODEL CONTINUES TO PREDICT BELOW NORMAL TEMPERATURES OVER MUCH OF THE U.S. - AS IT HAS FOR THE PAST FEW SEASONS - AND WILL BE DISCOUNTED BECAUSE IT WAS NOT CONSISTENT WITH THE SOLUTIONS FROM NUMERICAL MODELS RUN AT OTHER CENTERS AND CONFLICTED WITH THE FORECASTS FROM THE STATISTICAL TOOLS. CCA INDICATES TEMPERATURES IN THE WEST WILL BE BELOW THE MEAN OF THE LAST DECADE - BUT SINCE THERE IS A STRONG WARMING TREND THERE - ABOVE NORMAL TEMPERATURES ARE STILL SLIGHTLY FAVORED. DRY INITIAL SOIL MOISTURE CONDITIONS AND LOW SNOW COVER ARE A REAL CONCERN IN THE NATIONS MID- SECTION - BECAUSE IT WILL RESULT IN ANOMALOUSLY HIGH PORTION OF SOLAR ENERGY BEING CONVERTED TO SURFACE HEATING INSTEAD OF FOR EVAPORATION. THUS ABOVE NORMAL TEMPERATURES HAVE BEEN EXTENDED FURTHER EASTWARD THAN IN LAST MONTHS MAM FORECAST. BELOW NORMAL SSTS IN THE EASTERN NORTH PACIFIC WILL COUNTERACT THE RECENT WARMING TRENDS ALONG THE WEST COAST FROM ALASKA TO CALIFORNIA AND ARE ANTICIPATED TO BRING CONDITIONS THERE MORE IN LINE WITH THE 1971-2000 CLIMATOLOGY THAN TRENDS INDICATE. CCA PREDICTS BELOW NORMAL TEMPERATURES FOR INTERIOR ALASKA FOR MAM - MJJ WHICH CONFLICTS WITH RECENT TRENDS THERE - SUGGESTING THE ALASKAN TEMPERATURES WILL REFLECT THE LONG TERM NORMALS - AND HAVE BEEN REDUCED FROM TEMPERATURES PREDICTED ON LAST MONTHS OUTLOOK. ONLY MINOR CHANGES WERE MADE FROM THE PREVIOUS SET OF FORECASTS BEYOND THE SPRING. THE AREA OF ABOVE NORMAL TEMPERATURES FORECAST FOR JJA 2003 WAS EXPANDED SLIGHTLY IN THE EASTERN U.S. DUE TO SIGNALS FROM CCA - OCN AND SMLR. CCA - OCN - AND SMLR INDICATE WARMER-THAN-NORMAL TEMPERATURES FOR MOST SEASONS FROM MAM 2002 THROUGH MAM 2003 IN THE SOUTHWEST U.S. TEMPERATURES FOR OND 2002 THROUGH MAM 2003 REFLECT THE INFLUENCE OF TRENDS AND AN ANTICIPATED MATURE EL NINO EVENT. PROBABILITY ANOMALIES ARE MODEST SINCE THE STRENGTH OF THE WARM EVENT IS UNCERTAIN AT THIS TIME. IN THE ABSENCE OF TRENDS - THE WINTERTIME TEMPERATURES THROUGHOUT MUCH OF THE SOUTHERN U.S. TEND TO BE BELOW NORMAL IN A WARM ENSO EVENT - HOWEVER - WITH A STRONG WARMING TREND IN THE WEST - THE TEMPERATURES THERE WILL STILL SLIGHTLY FAVOR THE ABOVE NORMAL CATEGORY. TEMPERATURE TRENDS ARE WEAKER IN THE SOUTHEASTERN U.S. THAN IN THE WEST AND THE ENSO SIGNAL FOR BELOW NORMAL IS STRONG ENOUGH TO FAVOR BELOW NORMAL TEMPERATURES OVER FLORIDA NEXT WINTER AND SPRING. A WARM EVENT IS ASSOCIATED WITH NEAR TO BELOW NORMAL TEMPERATURES ALONG THE GULF COAST AND TEXAS - HOWEVER UNCERTAINTY IN THE STRENGTH OF THE WARM EVENT PREVENTS A CLEAR DETERMINATION OF THE CATEGORICAL FORECAST THERE - LEAVING THE ODDS CLOSE TO CLIMATOLOGY. . . . . . . . . . PRECIPITATION: SMLR AND CCA AND MOST NUMERICAL MODELS CONTINUE TO PREDICT BELOW MEDIAN PRECIP- ITATION IN THE SOUTHWEST U.S. FOR MAM 2002 RESULTING IN A MODEST INCREASE OF THE ODDS TOWARD BELOW MEDIAN PRECIPITATION THERE. THE NUMERICAL MODELS RUN AT NCEP AND OTHER FORECAST CENTERS FAVOR BELOW MEDIAN PRECIPITATION OVER MUCH OF THE SOUTHWESTERN U.S. - AS WELL AS FOR TEXAS AND FLORIDA. HOWEVER - THE PREDICTION OF DRY CONDITIONS IN THOSE REGIONS IN SPRINGTIME REQUIRES A STRONG CLIMATE SIGNAL SINCE THE SEASONAL TOTAL PRECIPITATION COME FROM ONLY A FEW PRECIPITATION EVENTS - SO CLIMATOLOGICAL ODDS ARE GIVEN. ABOVE MEDIAN PRECIPITATION IS FAVORED IN THE PACIFIC NORTHWEST IN AMJ AND MJJ DUE TO LONG- TERM TRENDS. WARM ENSO CONDITIONS TEND TO INHIBIT THE SOUTHWEST MONSOON - SO THE TREND-RELATED AREA OF BELOW MEDIAN PRECIPITATION WAS EXPANDED SLIGHTLY TO INCLUDE PORTIONS OF THE SOUTHWEST U.S.. A WET AREA FORECAST OVER FLORIDA DURING LATE SUMMER AND EARLY FALL IS THE RESULT OF OCN INDICATIONS. WARM ENSO CONDITIONS ARE NOW EXPECTED TO APPEAR EARLIER THAN THEY WERE A MONTH AGO SO SOME LATE SUMMER AND FALL ENSO SIGNALS HAVE BEEN ADDED TO THE CURRENT OUTLOOK. THESE INCLUDE A PREDICTION OF DRY CONDITION FOR PORTIONS OF THE MID- ATLANTIC STATES IN ASO AND SON 2003 - AND BELOW MEDIAN PRECIPITATION ALONG THE COAST IN THE PACIFIC NORTHWEST IN SON AND OND. BEGINNING IN OND 2002 AND CONTINUING THROUGH MAM 2003 EXTENSIVE AREAS OF ABOVE MEDIAN PRECIPITATION WITH MODEST PROBABILITIES ARE FORECAST ACROSS THE SOUTHERN PART OF THE NATION DUE TO EXPECTED EL NINO CONDITIONS. FORECAST DRYNESS CENTERED OVER THE NORTHERN ROCKIES IS FROM BOTH OCN AND EL NINO COMPOSITES. THE BELOW MEDIAN PRECIP- ITATION IN THE NORTH CENTRAL STATES AND THE OHIO VALLEY FROM JFM 2003 THROUGH MAM 2003 ARE ALSO DUE TO EXPECTED EL NINO INFLUENCES. THERE ARE NO RELIABLE FORECAST INDICATIONS FOR ALASKA PRECIPITATION TO DEPART FROM CLIMATOLOGICAL PROBABILITIES DURING ANY OF THE LEADS AT THIS TIME. FORECASTERS: D. UNGER AND R. MARTIN FOR A DESCRIPTION OF THE STANDARD FORECAST TOOLS - THEIR SKILL - AND THE FORECAST FORMAT PLEASE SEE OUR WEB PAGE AT: HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/MULTI-SEASON/ 13_SEASONAL_OUTLOOKS/TOOLS (USE LOWER CASE LETTERS) INFORMATION ON THE FORMULATION AND SKILL OF THE CAS FORECASTS MAY BE FOUND AT: HTTP://WWW.CPC.NCEP.NOAA.GOV/SOILMST/FORECASTS.HTML (USE LOWER CASE LETTERS) NOTES - THESE CLIMATE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF THEIR VALID PERIODS. WITHIN ANY GIVEN VALID PERIOD OBSERVATIONS AND SHORT AND MEDIUM RANGE FORECASTS SHOULD BE CONSULTED. THIS SET OF OUTLOOKS WILL BE SUPERSEDED BY THE ISSUANCE OF THE NEW SET NEXT MONTH ON THURSDAY MARCH 14 2002. 1971-2000 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 17 2001 FORECAST RELEASE. NNNN NNNN